Radio frequency identification (RFID) has been proposed for use in a number of applications in which an RFID tag is attached to an item and subsequently interrogated or read to obtain information regarding that item. For example, PCT Publication Nos. WO 00/10144 and WO 00/10122 describe various functions and applications for RFID systems, and exemplify the use of RFID tags in libraries. U.S. Pat. No. 5,963,134 also describes certain uses for RFID systems in libraries and for other applications. The present invention is related to the collection and management of data using RFID tags and systems.